With Britain in election mode, and Tony Blair backing Brown, a storm has blown over Blair's secretive web of companies, which includes Gibraltar.

"Tony Blair faced new questions over his secretive business empire last night as it emerged one of his companies has been licensed to operate in low-tax regimes abroad," said the Daily Mail. "Gibraltar, Lithuania and Liechtenstein are among the countries in which the former Prime Minister's new investment firm has obtained permission to trade."

Mr Blair - already thought to have channelled tens of millions of pounds through a complex web of companies since leaving office in June 2007 - is exploiting a loophole in the law to keep details of his earnings secret, say financial experts.

As the Tories called for an investigation into Mr Blair's complex business dealings, a spokesman for Mr Blair insisted the former Prime Minister was a 'UK resident taxpayer on all of his income'.